JP2007092668A - Arm type valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the assembling of an arm while minimizing an axial length in an arm type valve gear for adjusting a valve clearance by incorporating a lash adjuster. <P>SOLUTION: A fitting hole 14 is formed in a position facing the upper end of a valve stem 7 in an arm 1. A lash adjuster 20 incorporated in the fitting hole 14 is formed of a nut member 21, an adjusting screw 22 engaged with the nut member 21 so as to be threadable, an elastic body 23 pressing the adjusting screw 22 to a valve stem 7 side and a cap 24 press-fitted to the upper end outer periphery of the nut member 21. The axial length of the lash adjuster 20 is minimized by adopting cylindrical nut members 21 with both end openings. The assembling of the arm 1 in an engine can be facilitated by freely attachably/detachably mounting a holding tool 50 for keeping the adjusting screw 22 screwed to the end of an oscillating side in an arm 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an arm type valve gear in an internal combustion engine.

  In an arm type valve gear that opens and closes an intake valve or an exhaust valve (hereinafter simply referred to as a valve) by rotation of a cam, a camshaft is disposed above an arm that is swingably supported. A swing arm type valve operating device that opens the valve by pushing down the arm with the cam provided on the camshaft, and a camshaft is placed below the arm, and one end of the arm is pushed up by the cam provided on the camshaft There is a rocker arm type valve operating apparatus in which the valve is opened at the other end of the arm.

  In these arm type valve gears, valve clearance is automatically adjusted by incorporating a lash adjuster.

Conventionally known hydraulic lash adjusters described in Patent Document 1 and mechanical lash adjusters described in Patent Documents 2 and 3 have been known as lash adjusters incorporated into arm type valve gears.
Japanese Patent Laid-Open No. 10-231711 Japanese Utility Model Publication No. 5-21602. Japanese Utility Model Publication No. 2-114703

  By the way, in the hydraulic lash adjuster described in Patent Document 1, since engine oil is used as hydraulic oil, there are the following disadvantages.

Record
(1) Since engine oil is agitated by the crankshaft, air bubbles are often mixed in the oil, and when the oil mixed in the air bubbles is supplied to the pressure chamber of the lash adjuster, The amount of lift of the valve changes by compressing.
(2) The amount of dissolved air in the engine oil increases due to changes in temperature and pressure during engine operation, and air is separated from the oil and stored in the pressure chamber due to cooling after the engine is stopped. The amount changes.
(3) Since a reservoir chamber is required to maintain the function of the lash adjuster until the hydraulic pressure is secured when the engine is restarted, the lash adjuster becomes larger and heavier.
(4) Since the hydraulic oil is guided to the lash adjuster, it is necessary to process a small-diameter oil supply passage in the arm, which is extremely difficult to process.

  On the other hand, the mechanical lash adjusters described in Patent Documents 2 and 3 do not have the above-described problems of the hydraulic lash adjuster and are extremely advantageous. However, it is necessary to form a female thread for engaging the male screw member on the inner periphery of the bottomed cylindrical lifter body, and it is necessary to provide a tool escape at the closed end of the lifter body when tapping the female screw. There is an inconvenience that the axial length becomes long and the lash adjuster becomes large.

  The present invention provides an arm type valve operating apparatus in which a mechanical lash adjuster is incorporated between an arm and a valve stem, and the axial length of the lash adjuster is reduced in size and weight, and a stable valve lift amount is obtained. It is a technical subject to make it possible to facilitate the assembly of the arm to the engine.

  In order to solve the above problems, in the present invention, a fitting hole penetrating vertically is provided at the swinging side end portion of the arm that is swung by the rotation of the cam, and the lash incorporated in the fitting hole. In the arm type valve operating apparatus in which the valve stem is pushed down via an adjuster, the lash adjuster is fitted into the fitting hole, the upper end faces upward from the upper surface of the arm, and the lower surface of the arm faces the lower end. A nut member provided with a flange to be abutted with the screw, an adjustment screw having an external thread engaged with an internal thread formed on the inner periphery of the nut member, and an outer periphery of the upper end of the nut member An integrated cap that clamps the swing side end of the arm with the flange from above and below, and an elastic body that urges the adjustment screw toward the valve stem. Rotating means for preventing the nut member from rotating between the nut member and the arm is provided, and each of the female screw of the nut member and the male screw of the adjusting screw is subjected to an axial pushing load applied from the valve stem to the adjusting screw. The flank angle of the side flank is larger than the flank angle of the play side flank, and the saw blade screw is provided with a lead angle that moves in the axial direction while the adjustment screw rotates by pressing the elastic body, and swings the arm The structure which provided the holder which hold | maintains the said adjustment screw in the pushing state in the side edge part so that attachment or detachment was possible is employ | adopted.

  Here, in order to reduce the weight of the arm type valve gear, the arm is preferably made of an aluminum alloy.

  Further, in order to prevent the lash adjuster incorporated in the fitting hole of the arm from falling off more reliably, the cap is preferably integrated with the nut member by press-fitting, crimping or welding.

  In the arm type valve operating apparatus according to the present invention, when a protruding portion capable of contacting the upper end surface of the female screw formed on the nut member is provided on the outer periphery of the upper end portion of the adjusting screw, the arm type moving device is operated from the engine during maintenance around the engine. When the valve device is removed, the adjustment screw moves in the axial direction while rotating due to the pressing force of the elastic body, and the protruding portion comes into contact with the upper end surface of the female screw, so that the adjustment screw is removed while being engaged with the nut member. It can be stopped, and the reassembly of the arm type valve gear can be facilitated.

  In the arm type valve gear according to the present invention, a flat surface is formed on a part of the outer periphery of the flange as a detent means for preventing the nut member from rotating, and this flat surface is provided on the lower surface of the swing side end of the arm. Further, it is possible to adopt a structure in which the surface is engaged with the stopper surface.

  Further, in the arm type valve operating apparatus according to the present invention, when a tool insertion hole is formed in the end plate of the cap, and an engagement recess that can be engaged with the turning tool is provided on the upper end surface of the adjustment screw, the tool insertion hole Since the adjusting screw can be pulled up by inserting the turning tool and rotating the engagement tool with the tip of the turning tool engaged with the engaging recess, the pushing-up of the valve can be easily released.

  As described above, in the present invention, the cap is attached to the upper end portion of the nut member fitted in the fitting hole of the arm, and the arm swings between the cap and the flange provided at the lower end portion of the nut member. Since the nut member is fixed by holding the side end portion, it is possible to adopt a cylindrical member with both ends opening that does not require the escape of the tap tool as the nut member, and the short axial length is simple. A small lash adjuster with a simple structure can be obtained.

  Further, when the valve stem is pushed down, a reaction force applied from the valve stem to the lash adjuster can be received at the abutting portion between the flange of the nut member and the lower surface of the arm. For this reason, compared to the case where the shoulder is provided on the inner periphery of the fitting hole and receives the reaction force, the durability against breakage of the arm is high, and an aluminum alloy can be adopted as a material for forming the arm. It is possible to reduce the weight of the arm type valve gear.

  Furthermore, by preventing the nut member from rotating, the nut member vibrates even when the base circle of the cam is in contact with the arm and the valve opening force (pressing force) from the arm is not transmitted to the upper end surface of the valve stem. Can be prevented from rotating. For this reason, it is possible to obtain a stable valve lift amount and to prevent the inner periphery of the fitting hole provided in the arm from being worn by contact with the nut member.

  In addition, it is possible to prevent the adjustment screw from falling off at the stage of transportation before assembly of the arm to the engine by providing a detachable holding tool for holding the adjustment screw in the pushed state at the end of the swinging side of the arm. And the arm can be easily assembled to the engine.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the center portion of the arm 1 is supported by a rocker shaft 2, and can swing around the rocker shaft 2.

  A roller 4 is rotatably supported at one end of the arm 1 via a roller pin 3. The roller 4 comes into contact with a cam 6 provided on the camshaft 5, and the arm 1 is swung by the rotation of the cam 6. It is like that.

  Here, the valve stem 7 is slidably inserted into a guide hole 10 provided in the cylinder head 9, and a valve spring 12 is disposed between the spring retainer 11 attached to the upper end of the valve stem 7 and the upper surface of the cylinder head 9. The valve stem 7 is urged by the valve spring 12 in a direction in which the valve 8 is in close contact with the valve seat 13 (closed direction).

  The arm 1 is made of an aluminum alloy. The other end of the arm 1 is formed with a fitting hole 14 penetrating vertically at a position corresponding to the upper end of the valve stem 7, and a lash adjuster 20 for pushing down the valve stem 7 is incorporated in the fitting hole 14. Yes.

  As shown in FIG. 2, the lash adjuster 20 includes a steel nut member 21 fitted in the fitting hole 14, an adjustment screw 22 incorporated in the nut member 21, and the adjustment screw 22 as a valve. The elastic member 23 is urged toward the stem 7 and a steel cap 24 that closes the upper end opening of the nut member 21.

  The nut member 21 has a cylindrical shape with both ends open, and an internal thread 25 is formed on the inner periphery of the nut member 21 from substantially the center in the axial direction to the lower end. Further, a flange 26 is provided on the outer periphery of the lower end portion of the nut member 21, and the upper end portion of the nut member 21 faces upward from the upper end opening of the fitting hole 14 in a state where the flange 26 is in contact with the lower surface of the other end portion of the arm 1. It protrudes.

  The adjusting screw 22 has a male screw 27 on the outer periphery, and the male screw 27 is engaged with the female screw 25 of the nut member 21.

  Here, the female screw 25 of the nut member 21 and the male screw 27 of the adjusting screw 22 are such that the flank angle of the pressure side flank 28 that receives the axial pushing load applied from the valve stem 7 to the adjusting screw 22 is the flank of the play side flank 29. The sawtooth screw is larger than the corner, and the sawtooth screw is provided with a lead angle that moves in the axial direction while the adjustment screw 22 is rotated by pressing of the elastic body 23.

  Further, an engaging recess 30 in which a turning tool such as a driver can be engaged is provided on the upper end surface of the adjusting screw 22, while the lower end is a spherical surface 31 that is in point contact with the upper end surface of the valve stem 7.

  Further, a protrusion 32 is provided on the outer periphery of the upper end of the adjustment screw 22 by plastic working or the like. The projecting portion 32 can be engaged with the upper end surface of the female screw 25 formed on the inner periphery of the nut member 21, and the engagement of the adjusting screw 22 of the nut member 21 when the arm type valve gear is removed. It prevents falling down.

  The cap 24 is press-fitted into the outer periphery of the upper end portion of the nut member 21 and sandwiches the other end portion of the arm 1 from above and below with the flange 26 provided at the lower end portion of the nut member 21. Reference numeral 21 denotes an axially non-movable support. A tool insertion hole 33 is provided in the end plate 24 a of the cap 24.

  Between the nut member 21 and the arm 1, a detent means 40 for preventing the nut member 21 from rotating is provided.

  As shown in FIGS. 2 and 3, the rotation prevention means 40 forms a flat surface 41 on a part of the outer periphery of the flange 26 provided at the lower end of the nut member 21, while Is provided with a flat stopper surface 42, and the nut member 21 is prevented from rotating by engagement of the flat surface 41 with the stopper surface 42.

  Here, the arm 1 is transported in a state in which the lash adjuster 20 is incorporated in the fitting hole 14 at a stage before being assembled to the engine. During the transportation, the adjusting screw 22 advances while rotating due to the pressing of the elastic body 23, the projecting portion 32 comes into contact with the upper end of the female screw 25, and the tip end portion faces the outside from the opening end of the nut member 21.

  For this reason, when incorporating the arm 1 into the engine, it is necessary to incorporate the adjustment screw 22 into the arm 1 while being pushed into the nut member 21, which takes time and labor.

  In order to facilitate the incorporation, in FIGS. 4 and 5, a holding tool 50 is detachably attached to the swing side end portion of the arm 1 to hold the adjustment screw 22 in a pushed state.

  Here, the holder 50 includes a U-shaped engagement frame 51, which engages an engagement piece 52 provided on the upper side of the engagement frame 51 with the upper surface of the cap 24 and is provided on the lower side. The engaging piece 53 is engaged with the lower surface of the adjusting screw 22 so as to hold the adjusting screw 22 in a pushed state.

  The arm type valve operating apparatus shown in the embodiment has the above-described structure, and the assembly of the arm 1 to the engine is performed in a state in which the adjusting screw 22 is held in the pushed-in state by attaching the holding tool 50 as shown in FIG. Do.

  When the holder 50 is removed after the arm 1 is assembled, the adjusting screw 22 moves forward by rotation of the elastic body 23 and abuts on the upper end of the balm stem 7 to obtain the assembled state shown in FIGS. it can.

  In the assembled state shown in FIG. 1, when the camshaft 5 rotates and the roller 4 is pushed up by the protruding portion 6a of the cam 6, the arm 1 swings in the direction in which the other end moves downward, and the valve stem 7 Pushed down via the lash adjuster 20, the valve 8 opens.

  When the base circle 6b of the cam 6 comes into contact with the roller 4, the valve stem 7 is raised by the pressure of the valve spring 12, and the valve 8 is closed.

  When the valve 8 is opened and closed by swinging the arm 1, when the lash adjuster 20 pushes down the valve stem 7, a reaction force is applied from the valve stem 7 to the adjustment screw 22. When the valve stem 7 is pushed up by the valve spring 12, a pressing force is applied from the valve stem 7 to the adjusting screw 22, and the pressing force and the reaction force are the female screw 25 of the nut member 21 and the male screw 27 of the adjusting screw 22. The pressure side flank 28 is received.

  For this reason, the adjusting screw 22 does not rotate, and a pressing force and a reaction force are applied to the nut member 21 from the adjusting screw 22, and the pressing force and the reaction force are applied by the flange 26 of the nut member 21. It is received by the abutting surface on the lower surface of the other end of the arm 1 to be mated.

  In this way, the load such as the pressing force and reaction force applied from the valve stem 7 to the adjustment screw 22 of the lash adjuster 20 is received by the lower surface of the other end of the arm 1 and the other end is thick, so that it is durable. Is relatively expensive.

  For this reason, the arm 1 can be made of an aluminum alloy, and the weight of the arm type valve gear can be reduced.

  As shown in FIG. 2, when an axial groove 34 for dividing the female screw 25 is formed on the inner periphery of the nut member 21, when the pressure-side flank 28 of the female screw 25 and the male screw 27 comes into close contact with each other, the pressure-side flank Since the lubricating oil intervening between them can be released into the groove 34, the adhesion force of the pressure side flank 28 is increased, and the upward load applied to the adjusting screw 22 is reliably received by the pressure side flank 28. Can do.

  If a valve clearance is generated between the upper end surface of the valve stem 7 and the lower surface of the adjusting screw 22 due to thermal expansion of the cylinder head 9 accompanying the temperature rise of the internal combustion engine, the adjusting screw 22 is moved to the idle side by the pressing force of the elastic body 23. While rotating along the flank 29, the valve clearance is absorbed by moving in the axial direction. When the adjusting screw 22 receives a pushing force from the upper end surface of the valve stem 7, the adjusting screw 22 moves backward until the axial screw gap formed in the screw engaging portion of the male screw 27 and the female screw 25 is filled and further pushed. When a force is applied, the adjusting screw 22 is prevented from moving backward while receiving the above pushing force by the pressure side flank 28 that is in pressure contact with each other.

  On the other hand, when the distance between the upper end surface of the valve stem 7 and the lower surface of the adjusting screw 22 is reduced due to wear of the valve seat with which the valve 8 contacts and separates, the adjusting screw 22 changes in the axial direction loaded from the valve stem 7. When the valve is closed when the base circle 6b of the cam 6 comes into contact with the roller 4 due to the retreat, the valve 8 is brought into close contact with the valve seat 13 to prevent compression leakage. . At this time, the adjustment screw 22 is further pushed in from the position where the minimum value of the fluctuating load in the axial direction becomes 0, and does not move back further.

  In the arm type valve gear in the embodiment, the other end of the arm 1 is clamped from above and below by a cap 24 press-fitted into the outer periphery of the upper end of the nut member 21 and a flange 26 provided at the lower end of the nut member 21. As a result, the nut member 21 can be stably attached, and the nut member 21 can be a cylindrical member having both ends opened so that the relief of the tap tool can be eliminated. A compact lash adjuster with a directional length can be obtained.

  Here, in the embodiment, the cap 24 is attached by press fitting. However, by fixing the cap 24 to the nut member 21 by welding such as caulking or spot welding, the reliability of attaching the nut member 21 is further improved. Can be increased.

  Further, the flat surface 41 provided on the flange 26 of the nut member 21 is engaged with the stopper surface 42 formed on the lower surface of the arm 1 to prevent the nut member 21 from rotating, whereby the base circle 6b of the cam 6 is moved to the roller. 4, the nut member 21 is prevented from rotating even when the valve opening force is not transmitted from the arm 1 to the valve stem 7. Therefore, a stable valve lift amount can be obtained, and wear of the inner peripheral surface of the fitting hole 14 provided in the arm 1 can be prevented.

  Furthermore, by providing the protrusion 32 at the upper end of the adjustment screw 22, when the arm type valve gear is removed for maintenance around the engine, the adjustment screw 22 moves in the axial direction while rotating by the pressing of the elastic body 23. Thus, the protruding portion 32 comes into contact with the upper end surface of the female screw 25, and the adjustment screw 22 can be prevented from coming off in a state of being engaged with the female screw 25 by the contact.

  For this reason, the arm type valve gear can be easily reassembled. When the adjustment screw 22 pushes up the valve 8 during the assembly, the adjustment screw 22 is rotated to release the push-up. In this case, the adjusting screw 22 may be pulled up by inserting a turning tool into the tool insertion hole 33 provided in the cap 24 and engaging and rotating the tip of the turning tool with the engaging recess 30 of the adjusting screw 22. Therefore, the push-up of the valve 8 can be easily released.

  6 to 11 show another example of the holder 50 that holds the adjusting screw 22 in the pushed-in state. Each holder 50 is composed of a U-shaped engagement frame 51. 6 and 7, the upper engagement piece 52 of the engagement frame 51 is formed with a notch 54 in which a part of the cap 24 can be accommodated, and the upper engagement piece 52 is connected to the swing side end of the arm 1. The lower engaging piece 53 is engaged with the lower surface of the adjusting screw 22 to hold the adjusting screw 22 in the pushed-in state.

  8 and 9, a notch 55 having a size substantially corresponding to the valley diameter of the male screw 27 of the adjusting screw 22 is formed in the lower engaging piece 53 of the engaging frame 51, and the lower engaging piece 53 is formed. Is engaged with the play-side flank 29 at the lower part of the adjusting screw 22, and the upper engaging piece 52 is engaged with the upper surface of the cap 24 to hold the adjusting screw 22 in the pushed-in state.

  10 and 11, the upper engagement piece 52 of the engagement frame 51 is formed with a notch 54 in which a part of the cap 24 can be accommodated, and the lower engagement piece 53 is formed in the valley of the male screw 27 of the adjustment screw 22. A notch 55 having a size substantially corresponding to the diameter is provided, the upper engagement piece 52 is engaged with the upper surface of the swing side end of the arm 1, and the lower engagement piece 53 is connected to the lower part of the adjustment screw 22. The adjusting screw 22 is held in the pushed-in state by engaging with the play-side flank 29.

  In the embodiment, the rocker arm type valve operating device has been described as an example, but the arm type valve operating device is not limited to this. For example, a swing arm type arm type valve gear may be used.

Longitudinal front view showing an embodiment of an arm type valve gear according to the present invention Enlarged sectional view of the lash adjuster shown in FIG. Sectional view along line III-III in FIG. Sectional drawing which shows the set state of the holder which hold | maintains an adjustment screw in the pushing-in state The perspective view which decomposes | disassembles and shows the holder of FIG. Sectional drawing of the set state which shows the other example of a holder The perspective view which decomposes | disassembles and shows the holder of FIG. Sectional drawing of the set state which shows another example of a holder The perspective view which decomposes | disassembles and shows the holder of FIG. Sectional drawing of the set state which shows another example of a holder The perspective view which decomposes | disassembles and shows the holder of FIG.

Explanation of symbols

1 Arm 6 Cam 14 Fitting hole 20 Rush adjuster 21 Nut member 22 Adjust screw 23 Elastic body 24 Cap 24a End plate 25 Female screw 26 Flange 27 Male screw 28 Pressure side flank 29 Play side flank 30 Engaging recess 32 Projection 33 Tool insertion hole 40 Anti-rotation means 41 Flat surface 42 Stopper surface 50 Holder 51 Engagement frame 52 Engagement piece 53 Engagement piece

Claims (6)

  An arm type motion that has a fitting hole penetrating vertically on the swing side end of the arm that is swung by the rotation of the cam and pushes down the valve stem via a lash adjuster built into the fitting hole. In the valve device, the lash adjuster is fitted in the fitting hole, the upper end faces the upper surface of the arm, and the nut member is provided with a flange that abuts the lower surface of the arm at the lower end. An adjusting screw having a male screw engaged with a female screw formed on the inner periphery of the nut member on the outer periphery, and a fitting end of the nut member on the outer periphery of the upper end of the nut member. And an elastic body that urges the adjusting screw toward the valve stem, and prevents the nut member from rotating between the nut member and the arm. Rotation prevention means is provided, and the flank angle of the pressure side flank receiving the axial pushing load applied from the valve stem to the adjustment screw through the female screw of the nut member and the male screw of the adjustment screw is larger than the flank angle of the play side flank A serrated screw is provided with a lead angle that moves in the axial direction while the adjustment screw rotates by pressing the elastic body, and the adjustment screw is held in a pressed state at the swinging end of the arm. An arm type valve gear characterized in that a tool is detachably provided.   The arm type valve gear according to claim 1, wherein the arm is made of an aluminum alloy.   The arm type valve gear according to claim 1 or 2, wherein a protrusion capable of contacting an upper end surface of an internal thread formed on a nut member is provided on an outer periphery of an upper end portion of the adjustment screw.   The said rotation prevention means consists of a flat surface formed in the flange outer periphery of a nut member, and the stopper surface which is provided in the lower surface of the rocking | swiveling side edge part of an arm, and the said flat surface engages. The arm type valve gear according to any one of the above.   The arm type valve gear according to any one of claims 1 to 4, wherein a tool insertion hole is formed in the end plate of the cap, and an engaging recess is provided on an upper end surface of the adjusting screw to engage the tool.   The holder is formed of a U-shaped engagement frame having a pair of opposing engagement pieces on the upper and lower sides, and the upper engagement piece can be engaged with the upper surface of the cap or the upper surface of the swing side end of the arm. The arm type valve gear according to any one of claims 1 to 5, wherein the lower engaging piece is engageable with the lower surface of the adjusting screw or the play side flank below the male screw.

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